[Influence of clenbuterol on the sensory neurotrophic activity of denervated red and white muscles].

OBJECTIVE

To investigate the influence of clenbuterol on the expression of nerve growth factor (NGF) in denervated red and white muscles and the neurotrophic activity of the denervated muscles.

METHODS

Sixty-four Wistar rats, weighed 200-250 g, were divided into 8 groups (8 rats per group), including 4 experimental groups and 4 control groups. The denervated model was made in rats by dissection of sciatic nerves. Clenbuterol was given at a dose of 200 microg/kg per day in the experimental group, saline in the control group. The expression of NGF was measured with immunohistochemistry after 1, 3, 7 and 14 days of injury. The culture methods of dorsal root ganglions of the chick embryos were used to measure the neurotrophic activity of extracts of the muscles.

RESULTS

Compared with the control groups, the NGF content of gastrocnemius (GAS) increased on the 1st day (P<0.05) and the NGF content of soleus (SOL) increased greatly on the 1st, 3rd and 7th day after injury in the experimental groups (P<0.01). In the experimental groups, the NGF amount of GAS reached the highest value on the 1st day after injury (P<0.01) and then decreased gradually. And the NGF amount of SOL had slight difference between different time. The NGF content of the SOL was higher than that of GAS on the 7th day (P<0.05). The sensory neurotrophic activity of the extracts was similar between SOL and GAS.

CONCLUSION

Clenbuterol can change the expression of NGF in denervated muscles, but the change was different in SOL and GAS. The sensory neurotrophic activity of the denervated muscles were determined by all of the neurotrophic factors in them.